This invention relates primarily to universal adaptor plugs for use in wide-ranging geographic areas throughout the world and more particularly to electric connection devices enabling the use of small electric appliances, not only in the home country of the user, but also for connection to wall outlets in various other countries throughout the world.
When a user of small electric appliances travels from one country to the other throughout the world, it is often the case that each of the countries to which the user travels employs a different standard for the plugs and plug receptacles usable in that remote country.
Long ago, an adaptor plug involved the screwing in and screwing out of individual plug pins for several different plug systems. Of course, even with the aid of detailed operating instructions, the complication of changing plug pins, for instance, in the plug for a small electric appliance, was overwhelming, and presented a safety hazard when used by a non-skilled person.
A more sophisticated changeable plug pin system was developed by Peter Flohr in U.S. Pat. No. 4,856,999, issued Aug. 15, 1989, which involved a combination of spring-loaded contact arms and installation and screwing requirements for other parts, with various gripping surfaces, all of which provided a rather complex, occasionally unsatisfactory operational and safety hazard for the user.
In more recent years, Lee, in U.S. Pat. No. 5,159,545, issued Oct. 27, 1992, and the same inventor in U.S. Pat. No. 5,791,921, issued Aug. 11, 1998, improved the aforementioned drawbacks of adaptor elements, but not optimally. Indeed, the earlier Lee patent was disparaged by Lee himself in terms of the list of drawbacks of that earlier patent, at the introductory portion of the later patent.
The later Lee patent nevertheless used much of the technology and design of the earlier Lee patent, but substituted for the use of the user""s fingers for changing the plug pin to be used, from the plug pin already exposed, which, in the earlier version presented a particular dexterity requirement difficult to satisfy for the user. The substitution of design and technology in the later Lee patent involved the use of seesaw buttons for making the adjustment from one plug pin arrangement to another.
Accordingly, it is a primary object of the present invention to provide a convenient and user-friendly, yet safe, universal adaptor, for insertion to plug receptacles in different parts of the world.
A further and more particular object is to provide a universal adaptor, which does not require the screwing in or screwing out of any parts, nor any other complex installation or use procedures which would complicate or make hazardous the use of the item.
A further and more specific object is to provide a universal adaptor which enables use of the item, virtually without depending upon knowledge of which set of buttons or switches need to be touched or used to change the plug size for use in a particular country to which the user is travelling.
Other objects and advantages of the present invention which are provided in a universal adaptor plug which features a single rotary cam element and various cam followers, with the axis for mounting cams turnable by the user by rotating a single knob for projecting into useable position plug pins for use in the U.K., Ireland, some African countries, Hong Kong, Singapore and other countries; for use in Australia, New Zealand, China, Fiji and other countries; for use in North and South America, Japan and some Caribbean and other countries; and in Europe, the Middle East, and in some other African, Asian and Caribbean countries. The adaptor plug works with U.S., British and European appliances, and thereby provides a plug receptacle which admits plug pins sold with such appliances. More specifically, a rotatable knob for making the changes in terms of exposing different plug pins for insertion to a wall plug receptacle, or the like, is intended for use by manual rotation in a single direction to sequentially provide the plug pin exposure needed for the country visited by the user.